Spark-plug



A. T. CRANE.

SPARK PLUG.

APPLICATION FILED FEB. 2s, 1920.

Patented May 24, 1921.

z .uw I/.f ///N/ ////M/%/// UNITED STATES PATENT OFFICE.

ARTHUR T. CRANE, OF WATERIBUB'Y, CONNECTICUT, ASSIGNOR TO THE CHASE COM- PANIES INC., OF WATERBURY,

CONNECTICUT, A CORPGRATION.

SPARK-PLUG.

' Application filed Febr-nary To all whom t may concern:

Be it known that I, ARTHUR T.l CRANE, a citizen of the United States, residing at Waterbury, in the county of New Haven and State of Connecticut, have invented a new and useful Improvement in Spark-Plugs; and I do hereby declare the following, when taken in connection with the accompanying drawings and the characters of reference marked thereon, to be a full, clear, and exact description of the same, and which said drawings constitute part of this application, and represent, in

Figure 1, a view in side elevation of a spark-plug constructed in accordance with my invention. l

Fig. 2, a view thereofin vertical longitudinal central section showing one form of my improved two-part locking-ring in position to be forced into the locking-recess ofv the plug. l v

Fig. 3, a corresponding view showing the two parts of the locking-ring as molded by pressure into the locking-recess, the core or insulator in this View being shown partly in elevation and partly in section.r A

Fig. 4, a view in transverse section on the line 4-4 of Fig. 3.

Fig. 5, a reverse plan view of the terminal binding-cap.

Fig. 6, a detached plan view ofthe inner member of the locking-ring.

Fig. 7 a view thereof in side elevation.

Fig. 8, a detached plan view of the outer member of the locking-ring.

Fig. 9, a view thereof in side elevation.

My invention relates to an improved spark-plug, the object being to provide improved means for fastening the insulator or porcelain core in the shell, for centering the electrode wire in the insulator or core, and for the application of the binding-nut.

With these ends in view, my invention consists in a sparklug having its insulator or core secured in p ace within its shell by a multiple soft-metal locking-ring. My invention further consists in a spark-plug having its electrode wire provided with a centering-flange. My invention further conslsts in a spark-plug having its insulator or core provided with a sheet-metal terminal binding-cap for the reception of the upper end of the wire electrode and for the external ap lication to it of the binding-nut.

y invention further consists in certain Specifica-tion of Letters ratent.

Patented May 24, 1921. 25, 1920. serial No. 361,175.

i details of construction and combinations of as w1ll be hereinafter vdescribed and pointed out in the claims.

In carrying out my invention, as-herein shown, I employ a multiple locking-ring conslstlng of a. tubular inner member 5 and a tubular outer member 6 suiciently larger in dlameterthan the inner member to permit the two members to be telescoped one within the other, as shown in Fig. 2. These parts 5 and 6 are made of a suitable metal, soft enough to be molded under pressure, such as copper, which is by preference, though not necessarily, employed. As shown, the lower edges of these members are oppositely beveled, as seen at`7 and 8 in Fig. 2.

For the reception of this multiple packingrmg, the shell or housing 9 which may be of any approved form and construction, is formed within its upper edge with an undercut annular recess 10, whilethe insulator or porcelain core 11 is formed with a corresponding under-cut peripheral recess 12 positloned upon the exterior surface of the core so as to register .with the under-cut recess 10 of the shell when the core is positioned therein. The under-cut recesses 10 and 12 together form an annular locking-recess or chamber 13 of wedge-shaped cross-section, with its smaller end opening upward and outward.

For fastening the core 1l in the shell 9, the former is set into the latter, as shown in Fig. 2, after the gas-check gasket 14 has been interposed between their beveled shoulders 15 and 16, as also shown in Fig. 2. rressure is now applied to the upper ends of the soft metal parts 5 and 6, whereby they are driven down into the wedge-shaped locking-recess 13 and caused to re-shape themselves to conform to the shape thereof, as shown in Fig. 3. When the beveled lower edges of the said parts 5 and 6 strike the bottom wall of the recess 13, the respective parts are deflected inward and outward so as to facilitate this upsetting or molding operation. In its ultimate form, the multiple locking-ring completely fills the wedgeshaped annular recess or chamber 13 and effectively locks the core 11 in the shell 9 and supplements the gasket 14 as a gascheck for the spark-plug.

I do not limit myself to the use of two tubular units in the production of the multiple locking-ring, as the number of parts and their form'may be changed, this feature of my invention broadly comprehending the employment of a plurality of soft metal parts for the production of a locking-ring under pressure, rather than the employment of a one-piece soft metal blank which is more diiicult to cause to assume its ultimate form under pressure.

Coming now to the second feature of my invention, it consists in locating a beveled annular centering-flange 18 upon the wire electrode 19 of the plug, this flange being preferably formed integral with the electrode by upsetting the same. For the reception of the flange 18, the core is formed at its lower end with a concentric tapering recess 20, the bottom 21 of which conforms to the bevel of the flange. The bottom 21 of the said recess 20 opens into the lower end of a long concentric cement-chamber or bore 22 just enough larger than the electrode 19 to provide for a tubular envelop 23 of cement around the same. At its upper end, the cement-chamber 22 merges into a diminished centering-hole 24 for the reception and centering of the upper portion of the electrode 19 which projects upward through the top of the core, as will be described later on.

In assembling my improved spark-plug, the conical recess 2O is filled with a suitable cement which is also crowded into the cement-chamber 22. The electrode is then inserted into the core in which it will be centered by its flange 18 and by its upper end, so that it will have a cement envelop 28 of uniform thickness surrounding it throughout the length of the cement-chamber 22. The cement not only helps to center the electrode, but also forms a gas-check in which it is assisted by the flange 18.

The projecting upper end of the electrode wire 19 enters the tubular externally threaded stem 25 of a terminal binding-cap 26 made of sheet-metal, and spun over the upper end of the core, which is formed with an annular groove 27 for the reception of the inwardly turned retaining edge 28 of the cap which is held against rotation by theindentation of its edge, as at `32, into a corresponding recess 29 in the porcelain core, whereby the cap is securely held in place and also against rotation.

The threaded stem 2 5 of the cap 26 provides for the application of an ordinary binding-nut 30, generally applied, in suo spark-plugs, to the threaded projecting upper end of the electrode wire 19. The projecting lower end of the electrode wire is centered with respect to a ground terminal 31 mounted in the externally threaded lower ing with the said recess in the shell when the core is positioned therein, and a multiple locking-ring composed of a plurality of soft metal parts which are upset in the lockingrecess formed by the conjunction of the recesses in the core and shell.

3. In a spark-plug, the combination with the shell and core thereof, the same being formed with complementary under-cut recesses combining to produce an annular locking-recess, of a cross-sectionally wedgeshaped multiple locking-ring composed of a plurality of soft metal tubular parts, lower edges of which are beveled to facilitate being upset.

4. In a spark-plug, the combination with a shell formed within its upper edge with an under-cut annular recess, of a core formed with an under-cut peripheral recess registering with the said recess in the shell when the core` is positioned therein, and a twopart soft metal locking-ring located within the chamber formed by the said recesses.

In testimony whereof, I have signed this specification in the presence of two subscribing witnesses.

- ARTHUR T'. CRANE.

Witnesses:

JOHN S. NEAGLE, JOHN W. HARD.

the. 

